The atherosclerotic process begins in childhood and progresses through adult life resulting in coronary heart disease (CHD), stroke, and peripheral vascular disease. There is a need to identify young people at risk for premature atherosclerosis so that preventive measures can be instituted before occlusive vascular disease occurs. The ultrasonic measurement of carotid intimal-medial thickness (IMT) allows detection of early atherosclerosis and is related to incident CHD and stroke in older adults. In 1970, a population of school age children and adolescents was first examined in Muscatine, Iowa. A sample of 776 members of this longitudinal cohort, who are representative of the initial childhood population, is now aged 37 to 45 years. Their risk factors were measured in childhood, young adulthood and twice in later adult life, and they have undergone measurement of carotid IMT as well as electron beam computed tomography to identify coronary artery calcification (CAC). In this cohort, carotid IMT is significantly associated with CAC as well as current LDL cholesterol and systolic blood pressure, but only 14 percent of carotid IMT variability can be explained by these risk factors. Parents of the cohort have been assessed for cardiovascular morbidity and mortality. In this application the investigators propose to do the following: (1) examine the third generation to determine whether the offspring of cohort members with premature atherosclerosis and/or a familial history of cardiovascular disease have increased carotid IMT or elevated risk factors; (2) identify risk factors for progression of carotid IMT over four years in this cohort; and (3) measure putative risk factors for increased IMT (serologic evidence of Clamydia pneumoniae or cytomegalovirus infection, high sensitivity C-reactive protein, fibrinogen, plasminogen activator inhibitor-1 and glycosylated hemoglobin). The investigators state that the study has the potential of providing information which would allow identification of subjects at risk for atherosclerosis at an early age and may lead the way to interventions to halt or slow progression of atherosclerosis prior to the development of clinical disease.